docs: def is_perfect_consonant(note1, note2, include_fourths=True):
      """Return True if the interval is a perfect consonant one.
  
      Perfect consonances are either unisons, perfect fourths or fifths, or
      octaves (which is the same as a unison in this model).
  
      Perfect fourths are usually included as well, but are considered
      dissonant when used contrapuntal, which is why you can exclude them.
      """
      dhalf = measure(note1, note2)
      return dhalf in [0, 7] or include_fourths and dhalf == 5